In recent years, attention has been directed toward a double gate transistor having a channel and a source/drain region within a fin to restrain short channel effect (see JP-A (Kokai) No. 2006-100731.) However, there has never been proposed an example of reviewing in detail optimum structure of the double gate transistor having as large output resistance as possible.
For example, paragraph 0061 and FIG. 12 of the above patent document disclose an example in which the fin width on the source side is made thicker than that on the drain side, and the fin length on the drain side is made shorter than that on the source side, thereby balancing the resistance on the source side and that on the drain side. Since the structure in the above patent document is not formed in consideration of the output resistance, it cannot be guaranteed that the output resistance is increased with the structure in the above patent document.